Golf balls having at least two core layers formed from HNP compositions

Abstract

The present invention is directed to golf balls consisting of a multi-layer core and a cover. The multi-layer core includes at least one layer formed from a relatively soft or low modulus HNP composition and at least one layer formed from a relatively hard or high modulus HNP composition.

What is claimed is: 
     
       1. A golf ball comprising a core and a cover, wherein the core has an overall diameter of from 1.40 inches to 1.62 inches and consists of:
 (a) a center having a diameter of from 0.125 inches to 0.750 inches; 
 (b) an intermediate core layer formed from a first highly neutralized polymer composition; and 
 (c) an outer core layer formed from a second highly neutralized polymer composition; 
 wherein the material hardness of the first highly neutralized polymer composition is less than the material hardness of the second highly neutralized polymer composition; 
 wherein the intermediate core layer has a surface hardness less than the surface hardness of the center and the surface hardness of the outer core layer; and 
 wherein at least one of the first highly neutralized polymer composition and the second highly neutralized polymer composition comprises:
 an acid copolymer of ethylene and an α,β-unsaturated carboxylic acid; 
 an alkyl acrylate rubber selected from ethylene-alkyl acrylates and ethylene-alkyl methacrylates; 
 magnesium oleate present in an amount of 20 parts or greater per 100 parts of acid copolymer and akyl acrylate rubber combined; and 
 a cation source present in an amount sufficient to neutralize 110% or greater of all acid groups present in the composition. 
 
 
     
     
       2. The golf ball of  claim 1 , wherein the surface hardness of the center is 65 Shore C or greater. 
     
     
       3. The golf ball of  claim 1 , wherein the surface hardness of the center is 70 Shore C or greater. 
     
     
       4. The golf ball of  claim 1 , wherein the surface hardness of the intermediate core layer is from 20 Shore C to 70 Shore C. 
     
     
       5. The golf ball of  claim 1 , wherein the surface hardness of the outer core layer is from 80 Shore C to 90 Shore C. 
     
     
       6. The golf ball of  claim 1 , wherein the outer core layer has a thickness of from 0.010 inches to 0.150 inches. 
     
     
       7. The golf ball of  claim 1 , wherein the outer core layer has a thickness of from 0.030 inches to 0.070 inches. 
     
     
       8. The golf ball of  claim 1 , wherein the center is formed from a rubber composition. 
     
     
       9. The golf ball of  claim 1 , wherein the center is formed from a thermoplastic composition.